In late summer 1999, an outbreak of human encephalitis occurred in the northeastern United States that was concurrent with extensive mortality in crows (Corvus species) as well as the deaths of several exotic birds at a zoological park in the same area. Complete genome sequencing of a flavivirus isolated from the brain of a dead Chilean flamingo (Phoenicopterus chilensis), together with partial sequence analysis of envelope glycoprotein (E-glycoprotein) genes amplified from several other species including mosquitoes and two fatal human cases, revealed that West Nile (WN) virus circulated in natural transmission cycles and was responsible for the human disease. Antigenic mapping with E-glycoprotein-specific monoclonal antibodies and E-glycoprotein phylogenetic analysis confirmed these viruses as WN. This North American WN virus was most closely related to a WN virus isolated from a dead goose in Israel in 1998.

https://science.sciencemag.org/content/sci/286/5448/2333.full.pdf

Origin of the West Nile Virus Responsible for an Outbreak of Encephalitis in the Northeastern United States

https://espace.library.uq.edu.au/view/UQ:295107/UQ295107OA.pdf

The flavivirus NS1 protein: molecular and structural biology, immunology, role in pathogenesis and application as a diagnostic biomarker.

Antigen testing is now recognized as the method of choice for detection of Wuchereria bancrofti infections. Unlike tests that detect microfilariae, antigen tests can be performed with blood collected during the day or night. However, existing enzyme-linked immunosorbent assay (ELISA) tests for filarial antigenemia are difficult to perform in the field, and this has limited their use in endemic countries. In this article, Gary Weil, Patrick Lammie and Niggi Weiss review their experience with a new rapid-format filarial antigen test. They found that the ICT card test was very easy to perform and that it was comparable with ELISA for the detection of filarial antigen in sera from people with microfilaremia. The introduction now of an antigen test suitable for use in the field is especially timely, in that it may facilitate implementation of new strategies proposed by the World Health Organization for control and elimination of lymphatic filariasis.

The ICT filariasis test : rapid format antigen test for the diagnosis of bancroftian filariasis

West Nile virus (WNV) was isolated in a flock of 1,200 migrating white storks that landed in Eilat, a town in southern Israel, on August 26, 1998. Strong, hot westerly winds had forced the storks to fly under considerable physical stress before reaching the agricultural land surrounding the town. Most of the flock were fledglings, <1 year old, which had hatched in Europe. Thirteen dead or dying storks were collected 2 days after arrival and submitted to the laboratory for examination. Four WNV isolates were obtained from their brains. Out of 11 storks tested six days after arrival, three had WNV-neutralizing antibodies. Comparative analysis of full-length genomic sequences of a stork isolate and a 1999 flamingo isolate from the USA showed 28 nucleotide (nt) (0.25%) and 10 amino acid (0.3%) changes. Sequence analysis of the envelope gene of the stork isolate showed almost complete identity with isolates from Israeli domestic geese in 1998 and 1999 and from a nonmigrating, white-eyed gull in 1999. Since these storks were migrating southwards for the first time and had not flown over Israel, we assume that they had become infected with WNV at some point along their route of migration in Europe.

/pdf/introduction-of-west-nile-virus-in-the-middle-east-by-xiw7zb79fi.pdf

Introduction of West Nile Virus in the Middle East by Migrating White Storks

C57BL/6J mice infected intravenously with the Sarafend strain of West Nile virus (WNV) develop a characteristic central nervous system (CNS) disease, including an acute inflammatory reaction. Dose response studies indicate two distinct kinetics of mortality. At high doses of infection (10(8) PFU), direct infection of the brain occurred within 24 h, resulting in 100% mortality with a 6-day mean survival time (MST), and there was minimal destruction of neural tissue. A low dose (10(3) PFU) of infection resulted in 27% mortality (MST, 11 days), and virus could be detected in the CNS 7 days postinfection (p.i.). Virus was present in the hypogastric lymph nodes and spleens at days 4 to 7 p.i. Histology of the brains revealed neuronal degeneration and inflammation within leptomeninges and brain parenchyma. Inflammatory cell infiltration was detectable in brains from day 4 p.i. onward in the high-dose group and from day 7 p.i. in the low-dose group, with the severity of infiltration increasing over time. The cellular infiltrates in brain consisted predominantly of CD8(+), but not CD4(+), T cells. CD8(+) T cells in the brain and the spleen expressed the activation markers CD69 early and expressed CD25 at later time points. CD8(+) T-cell-deficient mice infected with 10(3) PFU of WNV showed increased mortalities but prolonged MST and early infection of the CNS compared to wild-type mice. Using high doses of virus in CD8-deficient mice leads to increased survival. These results provide evidence that CD8(+) T cells are involved in both recovery and immunopathology in WNV infection.

CD8+ T Cells Mediate Recovery and Immunopathology in West Nile Virus Encephalitis

Despite being identified in 1938, many aspects of the pathogenesis and epidemiology of fibropapillomatosis (FP) in marine turtles are yet to be fully uncovered. Current knowledge suggests that FP is an emerging infectious disease, with the prevalence varying both spatially and temporally, even between localities in close proximity to each other. A high prevalence of FP in marine turtles has been correlated with residency in areas of reduced water quality, indicating that there is an environmental influence on disease presentation.

Chelonid herpesvirus 5 (ChHV5) has been identified as the likely aetiological agent of FP. The current taxonomic position of ChHV5 is in the family Herpesviridae, subfamily Alphaherpesvirinae, genus Scutavirus. Molecular differentiation of strains has revealed that a viral variant is typically present at specific locations, even within sympatric species of marine turtles, indicating that the disease FP originates regionally. There is uncertainty surrounding the exact path of transmission and the conditions that facilitate lesion development, although recent research has identified atypical genes within the genome of ChHV5 that may play a role in pathogenesis. This review discusses emerging areas where researchers might focus and theories behind the emergence of FP globally since the 1980s, which appear to be a multi-factorial interplay between the virus, the host and environmental factors influencing disease expression.

/pdf/a-review-of-fibropapillomatosis-in-green-turtles-chelonia-4wlxdrqy1h.pdf

A review of fibropapillomatosis in Green turtles (Chelonia mydas).

Little is known about the process whereby the emetic toxin (or cereulide) of Bacillus cereus is produced. Two cereulide-producing strains of B. cereus were cloned and sequenced following polymerase chain reaction (PCR) amplification with primers that were specific for conserved regions of non-ribosomal peptide synthetase (NRPS) genes. The cloned regions of the B. cereus strains were highly homologous to conserved regions of other peptide synthetase nucleotide sequences. Primers were designed for two variable regions of the NRPS gene sequence to ensure specificity for the emetic strains. A total of 86 B. cereus strains of known emetic or non-emetic activity were screened using these primers. All of the emetic strains (n=30) displayed a 188 bp band following amplification and gel electrophoresis. We have developed an improved method of identifying emetic strains of B. cereus and provided evidence that cereulide is produced by peptide synthetases.

Evidence for non‐ribosomal peptide synthetase production of cereulide (the emetic toxin) in Bacillus cereus

Previous studies have shown that antibodies produced against strategic flavivirus epitopes play an important role in recovery and immunity. Definition of the conformation and location of these epitopes and the degree of their conservation among flaviviruses is important to understanding the humoral response to flavivirus infection. In this study we have examined epitopes recognized by 14 monoclonal antibodies (MAbs) produced to the envelope (E) and non-structural (NS1) proteins of Murray Valley encephalitis virus (MVE). These antibodies were analysed for specificity, neutralization, haemagglutination inhibition (HI) and competitive binding. We have identified six distinct epitopes on the E protein which are located in four non-overlapping domains. MAbs to epitopes in one domain neutralized virus, were specific for MVE and Japanese encephalitis virus, and reacted with epitopes resistant to reduction. Two other E domains, one specific to MVE and the other shared by all flaviviruses, also contained neutralization sites and were stabilized by disulphide bonds. The fourth domain on E was conserved among the flaviviruses, sensitive to SDS denaturation and did not induce neutralizing antibody. Studies with MVE NS1 MAbs revealed that they were mostly type-specific, unreactive with conserved epitopes, and unreactive in HI and neutralization tests. The six epitopes identified on NS1 did not overlap and represent antigenic domains either resistant or sensitive to reduction. Immunoblotting of viral proteins in MVE-infected C6/36 cells revealed two distinct forms of NS1 and high Mr proteins of 97K and 108K that represented disulphide-linked heterodimers of E and NS1.

Epitope Analysis of the Envelope and Non-structural Glycoproteins of Murray Valley Encephalitis Virus

Objective: To identify and gain an understanding of the influenza viruses circulating in wild birds in Australia.

Design: A total of 16,303 swabs and 3782 blood samples were collected and analysed for avian influenza (AI) viruses from 16,420 wild birds in Australia between July 2005 and June 2007. Anseriformes and Charadriiformes were primarily targeted.

Procedures: Cloacal, oropharyngeal and faecal (environmental) swabs were tested using polymerase chain reaction (PCR) for the AI type A matrix gene. Positive samples underwent virus culture and subtyping. Serum samples were analysed using a blocking enzyme-linked immunosorbent assay for influenza A virus nucleoprotein.

Results: No highly pathogenic AI viruses were identified. However, 164 PCR tests were positive for the AI type A matrix gene, 46 of which were identified to subtype. A total of five viruses were isolated, three of which had a corresponding positive PCR and subtype identification (H3N8, H4N6, H7N6). Low pathogenic AI H5 and/or H7 was present in wild birds in New South Wales, Tasmania, Victoria and Western Australia. Antibodies to influenza A were also detected in 15.0% of the birds sampled.

Conclusions: Although low pathogenic AI virus subtypes are currently circulating in Australia, their prevalence is low (1.0% positive PCR). Surveillance activities for AI in wild birds should be continued to provide further epidemiological information about circulating viruses and to identify any changes in subtype prevalence.

Australian surveillance for avian influenza viruses in wild birds between July 2005 and June 2007

Five monoclonal antibodies (MoAb) were produced to the envelope (E) protein of Kunjin (KUN) virus. Three of these were specific for the KUN/West Nile complex, and two reacted with epitopes that were common to the flavivirus family. These MoAb defined at least four distinct epitopes on the E protein of KUN virus. Eight MoAb were also produced to unidentified proteins of Kokobera (KOK) virus. Seven were specific for KOK, while the remaining antibody cross-reacted with Stratford virus and an unregistered flavivirus CS946. The application of these MoAb to arboviral surveillance is discussed.

Graham Burgess

Papers

A review of fibropapillomatosis in Green turtles (Chelonia mydas).

Evidence for non‐ribosomal peptide synthetase production of cereulide (the emetic toxin) in Bacillus cereus

Epitope Analysis of the Envelope and Non-structural Glycoproteins of Murray Valley Encephalitis Virus

Australian surveillance for avian influenza viruses in wild birds between July 2005 and June 2007

Monoclonal antibodies to Kunjin and Kokobera viruses